基于超声波声速法的气液两相流湿度测量技术可行性研究

蒸汽是汽轮机的重要工作介质，蒸汽湿度会直接影响汽轮机组的安全和经济运行，因此实现蒸汽湿度的可靠、在线测量具有重要意义。为了验证基于超声波声速法的气液两相流湿度测量技术可行性，首先通过引入一些必要假设条件，初步提出了声速法湿度测量技术理论模型，理论分析表明，介质湿度仅是关于声速、温度和压力3个直接变量的函数，直接测量变量较少，模型整体结构比较清晰；在此基础上，以空气-液滴为对象开展冷态实验研究，进一步验证了该技术方案的可行性。实验研究结果表明，随着湿度的增加，介质声速逐渐减小，两者具有较强的线性关系，在0~20%的湿度范围内，声速变化量约为22 m/s，基于超声波声速法的两相流湿度测量技术具有一定可行性。 

Feasibility Study of Two-Phase Flow Wetness Measurement by Ultrasound Velocity Technology

Saturated steam is an important working medium for steam turbines. The wetness of the steam will directly affect the safe and economic operation of steam turbines. Therefore, it is of great significance to realize the reliable on-line measurement of the steam wetness. In order to verify the feasibility of two-phase flow wetness measurement technology based on ultrasonic sound velocity method, this paper firstly introduces some necessary assumptions, and proposes a theoretical model of wetness measurement by sound velocity method. Theoretical analysis shows that the medium wetness is the function of sound velocity, temperature and pressure. The function of direct variables has fewer direct measurement variables, and the overall structure of the model is relatively simple. On this basis, the cold-state experimental study is carried out with air-droplet as the object to further verify the feasibility of the model. The experimental results show that with the increase of wetness, the sound velocity of the medium gradually decreases, and the two have a strong linear relationship. In the wetness range of 0~20%, the speed of sound change is about 22 m/s. The two-phase flow wetness measurement scheme based on the ultrasonic sound velocity method is with certain feasibility.